Sealing large gaps under high pressure is often needed in various applications. Many of these applications are dynamic, where the seal must compensate for an offset and/or flexing of the mating components. One such application is for tools used in directional/horizontal down-hole oil, gas and geothermal drilling. Steerable down-hole drills use castellated sections to transfer rotational motion while maintaining flexibility of the system. The joints between the castellated sections have extrusion gaps between the teeth of the castles and large open areas adjacent the exterior walls to allow the two sections to flex with respect to each other. To seal across the two sections, a diaphragm is typically used to keep high pressure (1500 psi) oil in and high pressure (5000 psi) mud out. The seal typically must be able to withstand temperatures up to about 200° C. Extrusion of the diaphragm between the teeth is a primary cause of sealing failure.